The IGOSS Sea Level Program in the Pacific was established for the purpose of making monthly mean sea level data available to a wide circle of users in a timely fashion, and to generate products that would be valuable for scientific analysis of climate-related ... processes. A pilot project started in June, 1984 and a permanent program was established in 1988. During the pilot project and in the first year of the permanent program, maps of the sea level deviations from the mean sea level were produced without fail beginning in June 1984 (ISLPP.DEVIATIONS, see below). In January 1988, maps were produced of the anomaly of sea level from the 1975 to 1986 mean annual cycle of sea level (ISLPP.ANOMALIES). This anomaly is also corrected for the inverted barometer effect using the atmospheric pressure fields computed at the National Meteorological Center.

Beginning in 1997, the mean sea level and annual cycle are referenced to the period 1975 - 1995. Data from previous years have been updated using the new reference means.

In addition to these basic products, additional products were developed during the pilot project. These products include time series of the volume of the tropical Pacific Ocean (ISLPP.VOLUME, published quarterly) and indices of the equatorial current system (ISLPP.CURRENTS and ISLPP.TOPOGRAPHY, published annually). The volume time series has received much attention because of its importance for El Nino prediction and analysis.

The time series at each station is preceded by one header record, which includes the station name and location, followed by a series of data records, each containing data for one year. These data records contain the station name, the year and the 12 monthly values of the appropriate quantity.

ISLPP.DEVIATIONS

This file contains the time series of the deviations of sea level from the 1975 to 1995 mean sea level value computed at each station. The time series cover the period 1975 to 1997. Large linear trends were found at five stations and are corrected for in this dataset. The five stations affected are Kushimoto, Aburatsu, and Naha in Japan, Davao in the Philippines, and Seldovia in Alaska.

ISLPP.PC_DEVIATIONS

This file contains the time series of the pressure-corrected deviations of sea level from the 1975 through 1995 mean sea level value computed at each station. The time series cover the period 1975 through 1997. Large linear trends were found at five stations and are corrected for in this data set. The five stations affected are Davao in the Philippines, Kushiro in Japan Suva in Fiji and Seldovia, Yakutat in Alaska. Units for the pressure-corrected sea level deviations are millimeters, and missing data points are set to a value of 9999.

ISLPP.ANOMALIES

This file contains the anomalies of sea level corrected for the atmospheric pressure. Anomalies of sea level are computed by subtracting the mean annual cycle of the sea level variation that is estimated using data from 1975 to 1995. Atmospheric pressure corrections are derived from the fields computed at the National Meteorological Center. The time series of the pressure-corrected sea level anomaly cover the period 1975 to 1997. Large linear trends were found at five stations and are corrected for in this dataset. The five stations affected are Kushimoto, Aburatsu, and Naha in Japan, Davao in the Philippines, and Seldovia in Alaska.

ISLPP.CURRENTS and ISLPP.TOPOGRAPHY

These files contain indices of the equatorial Pacific currents and estimates of the equatorial ridge and trough topography that are used to derive the current indices. Current indices are provided for the North Equatorial Countercurrent, the North Equatorial Current, and for the portions of the South Equatorial Current lying north and south of the equator. The current indices are computed by perturbing the meridional profile of mean surface dynamic height with the monthly mean time series of the sea level variations and calculating the appropriate ridge to trough difference for each current for each month. The mean values of the indices have not been removed from the time series. The calculation of these indices is discussed in greater detail in Wyrtki (74); see reference section.

ISLPP.VOLUME

This file contains the monthly time series of the variations in the upper layer volume of the tropical Pacific between 15N and 15S. The volume is computed from a gridded field of the sea level deviations via a one and a half layer approximation for the vertical structure of the tropical Pacific. Further details of the calculation are given by Wyrtki (87); see reference section. The units for the volume changes are 10 to the 12th cubic meters, and the variations are relative to a mean value of about 7000 of these units. The annual cycle has not been removed from the volume deviation time series.

There are seven files available: README, ISLPP.DEVIATIONS, ISLPP.PC_DEVIATIONS, ISLPP.ANOMALIES, ISLPP.CURRENTS, ISLPP.TOPOGRAPHY, and ISLPP.VOLUME. The README file contains a somewhat more detailed version of the information given in this summary.

We ask that you help the University of Hawaii monitor the success of their effort to enhance the access to IGOSS products. To do this, please let them know what data you have copied, and make comments or suggestions for improvement. You can send mail messages to Mark Merrifield (markm@soest.hawaii.edu), or to Shikiko Nakahara (nakahara@kia.soest.hawaii.edu).

If you cannot use the anonymous ftp, contact the University of Hawaii using the information given below in the personnel section.